7 Tips to Support Your Immune System Through Diet
by Olga Hamilton
It is well-known that a good diet and the right nutrients are essential for our immune system to function properly. Our body cannot make or create certain essential nutrients, which is why it is absolutely critical to make sure your diet supplies those nutrients. Make every bite count – think of the nutrient density of the foods, and choose wisely.
Nutrient-dense foods are high in nutrients but relatively low in calories, so you get a high nutrient-per-calorie ratio. Nutrient-dense foods contain vitamins, minerals, complex carbohydrates, lean protein, and healthy fats. Reduce ’empty’ calories, i.e. foods that provide calories but no nutritional value, such as processed foods, sweets, desserts, biscuits, cakes, sweetened drinks and sugar-laden cereals and dairy products with added sugar.
Instead, set yourself daily targets to consume nutrients.
Aim to consume 500-600g of vegetables per day. It does not matter whether they are cooked from frozen, boiled, steamed, roasted, stewed, grilled, raw, or come out of a tin – everything counts. Vegetables provide one of the most famous immune-supporting vitamins, vitamin C. It assists in many functions of the immune system cells, contributes to epithelial barrier function against pathogens and can enhance microbial killing.
Include oily fish, and aim for 4-5 portions per week. One portion is 120g, approximately the size of a small tin of sardines. Oily fish famously provide us with Omega-3 essential fatty acid, which has important immune-regulatory functions, especially in our defence against bacterial and viral infections. Eat a variety: anchovies, sardines, herring, mackerel, salmon, trout, kippers and fresh tuna are all easy-to-find options.
Make sure you consume enough protein. A simple calculation is 1g of protein per 1kg of your weight per day. For a 70kg person, that would be 70g of protein per day. 120g of sardines provide 30g of protein, which is the same amount as 100g of chicken breast. One boiled medium egg has 13g of protein. If you are vegan, taking a vegan protein powder would provide you with your daily requirements.
Get tested for deficiencies. There is evidence to suggest that nutritional deficiencies can weaken our immune system and make us more vulnerable to infections. DNA testing can reveal where you may require additional quantities of certain macro- and micronutrients to help prevent any potential nutritional deficiencies. Get yourself tested to assess your genetic nutrient requirements – genetic tests are very easy to do at home, just requiring your saliva. A DNA test will analyse how your body metabolises various essential nutrients and will provide recommendations for the optimal level of nutrient intake.
Focus on immune-supporting micronutrients such as the following:
Selenium: Brazil nuts, seafood, and organ meats are the richest food sources of selenium. Your recommended daily allowance is 55 micrograms, which translates to 50g of tuna or just one brazil nut per day. Do keep in mind that our selenium requirements are affected by our genetics and some people may need to double their intake to keep their selenium levels in the optimal range.
Zinc: Zinc is considered a “gate-keeper of immune function”. Zinc supplementation has been found to benefit patients suffering from viral and bacterial infections among other conditions. Oysters contain more zinc than any other food, but red meat, poultry, beans, nuts, certain types of seafood (such as crab and lobster) provide good amounts.
The recommended daily allowance is 11 milligrams for males and 9mg for females, which translates to just 13g of oysters, 135g of beef or 128g of pumpkin seeds per day. Keep in mind that the presence of phytates in whole-grain breads, cereals, legumes, and other foods can bind zinc and inhibit its absorption. Thus, the bioavailability of zinc from grains and plant foods is lower than that from animal foods.
Vitamin A: Liver and fish oils contain the highest concentration of preformed Vitamin A. Other sources of preformed vitamin A are dairy products and eggs, most dietary provitamin A (a precursor of vitamin A, also called beta-carotene, which our body converts to active form) comes from leafy green vegetables, orange and yellow vegetables, tomato products, fruits, and some vegetable oils. The recommended daily allowance is 900 micrograms for males and 700mcg for females, which translates to just 12g of beef liver, 75g of sweet potato or 250g of cooked spinach per day. Do keep in mind that our vitamin A requirements are affected by our genetics as some people cannot convert dietary provitamin A into its active form efficiently and may need to supplement preformed Vitamin A.
Vitamin D – the sunshine vitamin. While we are still allowed to go for a walk or exercise in a park once per day, do use this opportunity to top up your vitamin D levels. We all know that vitamin D is one of the most important vitamins that supports immune system. Vitamin D deficiency is associated with increased susceptibility to infection. Vitamin D exerts its effect through vitamin D receptor and variants in vitamin D receptor (VDR) gene are shown to affect vitamin D levels and function. Thus, to compensate for this, individuals with VDR variants (different version of vitamin D receptor gene) are recommended to increase their vitamin D intake above recommended daily allowance (RDA) that is accepted to be sufficient to prevent deficiency in the general population.
Supplement appropriately. Supplementation is a very good idea during this time and acts as an insurance policy just in case you are deficient in any of the essential nutrients. Research has shown that people who do not meet their individual body’s requirements for one or more essential nutrients are more likely to be at risk of picking up infections. Moreover, these infections can then last longer and be more severe. When the nutrient deficiencies are corrected with supplementation, the immune system function tend to improve, people become more resistant to infections and even deal with infection more efficiently.
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